The present invention relates to an isolation valve assembly for connection between a main flow pipeline and at least one fluid sensor, gauge or the like. The invention is particularly, but not exclusively, concerned with a double block and bleed isolation valve.
It is often necessary to determine characteristics of fluid flow in a main flow pipeline, such as, for example fluid pressure or temperature. The traditional approach to sensing such parameters is to connect a sensor or gauge to a main flow pipeline via an isolation valve assembly. The valve assembly is used to isolate the sensor temporarily from the main flow pipeline in the event that the sensor needs servicing or replacing.